Bolt mechanism for rifles



Dec. 5, 1944. J. D. PEDERSEN BOLT MEHANISM FOR RIFLES 5 Sheets-Sheet lOriginal Filed July 29, 1939 INVENTOR klamfifaf/Psfw BY @m #m ATTO R NEYS Dec. 5,V 1944.

J. D. PEDERSEN l BOLT MECHANISM FOR RIFLES 5 sheets-sheet 2 OriginalFiled July 29, 1939 Dec. 5, 1944. D, PEDERSEN 2,364,548

BOLT MECHANISM FOR RIFLES Original Filed July 29, 1939 5 Sheets-Sheet 3eff 202 @vd/mi2 ATTORNEYS J. D. PEDERSEN BOLT MECHANISM FOR RIFLESOriginal Filed July 29, 1939 5 Sheets-Sheet 4 2f'. @5425 jp. 26. /40 /44l @a l /42 /444 INVENTOR nfo/m/ffaf/wfw @vim ATTDRNEYS Dec. 5, 1944. J,D; PEDERSEN 2,364,548

BOLT MECHANISM FOR RIFLES Original Filed July 29, 1939 5 Sheets-Sheet 5g l 4 i705 0310/ J/ ATTORNEYS the carrier.

Patented Dec. 5, '.1944

BOLT MECHANISM FOR RIFLES John D. Pedersen, Jackson, Wyo. Originalapplication July 29, 1939, Serial No.

Divided and this application March 13, 1943, Serial No. 478,996

2 Claims.

The present invention relates to an improvement in bolt mechanism forrines, and more particularly rifles of the semi-automatic type such l asshown in my copending application Serial No.

287,221, led July 29, 1939, Patent No. 2,330,737, dated September 28,1943, of which this application is a division.

The bolt mechanism of the present improvement is of the combined rotaryand reciprocatory type, being `rotated between locked and unlockedpositions and being reciprocated for opening and closing the breech andmagazine chamber. is presented herein in two alternate forms, one ofwhich is an assembly of cover, carrier and bolt and the other merely anassembly of cover and bolt, this second form showing a cover whichcombines its own functions with that of a carrier. Both of these formspresent a substantially smooth uninterrupted closure for the breech toprevent the intrusion of dirt.

Referring to the drawings which show said bolt mechanism and itspreferred embodiments,

Fig. 1 is a longitudinal section through the receiver and part of thestock and barrel of a rifle showing the bolt mechanismin breech closingposition;

Fig. 2 is a similar longitudinal section showing the bolt mechanism inthe open and fully retracted position;

Fig. 3 is a top View oi the bolt assembly;

Fig. 4 is a section through the bolt assembly generally on line 4-4 ofFig. 7;

Fig. 5 is a rear end View of the bolt assembly, the bolt being in itsunlocked position;

Fig. 6 is a section on line 6 6 of Fig. 4;

Fig. 7 is a front end View of the bolt assembly, the bolt being in itsunlocked position;

Fig. 8 is a fragmentary View of the carrier front end, showing in dottedlines the position of the ejector plunger when the bolt is in theunlocked position;

Fig. 9 is a similar fragmentary front View of In this View the ejectorplunger (dotted) is in the position for detaching the bolt from thecarrier;

Fig. 10 is a fragmentary section on line Ill- I0 of Fig. 7 to give aside View of the bolt stop shoulders;

Fig. 11 is a projected View of the stopping shoulders of Fig. 10 lookingin the direction of the dotted projection lines connecting said ngures;

Fig. 12 is a rear end View of the bolt shown in Fig. 10;

Fig. 13 is a fragmentary section through the ItV receiver near its frontend, to show thefront end View of the bolt in its locked position;

Fig. 14 is a fragmentary section through the receiver near its frontend, to show lthe front end View of the bolt in its unlocked position;

Fig. 15 is a section on line l5--l5 of Fig. l. In this position the boltis locked;

Fig. 1,;6 is a section on line iB- of Fig. 1. In this position the boltis locked;

Fig. 17 is a section on line II-I'I of Fig. 2. In this position the boltis unlocked;

Fig. 18 is a section on line IB-lil of Fig; 2. In this position the boltis unlocked;

Fig. 19 is a fragmentary unrolled section on line I9-l9 of Fig. 16,showing the ring pin in its forward position;

Fig. 2O is a fragmentary unrolled section on line 20-20 of Fig. 1'8,showing the ring pin in its retracted position;

. Fig. 21 is a fragmentary unrolled section on line 2I-2I of Fig. 13,showing the fully locked position of the bolt;

Fig. 22 is a fragmentary unrolled section similar to Fig. 21, butshowing the bolt in nearly its unlocked position;

Fig. 23 is a fragmentary unrolled section on line 23--23 of Fig. 14,showing the fully unlocked position of the bolt;

Fig. 24 is a fragmentary unrolled section on line 2li- 24 of Fig. 13,showing the left lug of the bolt in the locked position;

Fig. 25 is a fragmentary unrolled section simi lar to Fig. 24, butshowing the bolt in nearly its unlocked position;

Fig. 26 is a fragmentary unrolled section on line 26--26 of Fig. 14,showing the ybolt fully unlocked;

Fig. 27 is a top View of the assembled bolt and carrier of alternateconstruction. The bolt is in the unlocked position;

Fig. 28 is a section on line 26-28 of Fig. 3l;

Fig. 29 is a rear View of the assembled bolt, in the unlocked position;

Fig. 30 is a section on line S--SD of Fig. 28;

Fig. 31 is a front View of the assembled bolt;

Fig. 32 is a fragmentary unrolled section on line 32-32 of Fig. 29, :butwith boli; locked and firing pin forward;

Fig. 33 is a fragmentary unrolled section on line 32- -32 of Fig. 29,showing the bolt unlocked and the firing pin retracted;

Fig. 34 is a section on 1ine 30-33 of Fig. 28, but

with the bolt turned to its position ready to deguard member. Otherdetails of this mechanism form no part of the subject matter claimed in`this application and are more fully described in my companionapplication cf which this is a division.

In Fig. 1 the breech action is in closed position,

in Fig. 2 in open position. VThe breech actionv comprises a'reciprocableand rotatable bo-lt |30. which is provided with a pair of oppcsitelylocated breech locking lugs |40, |4I, Fig. 3, adapted to lock. ahead ofthe receiver locking shoulders |42,

|43: locked po-sition, While Fig." 14 shows the bolt rotated to itsunlocked position and ready to be moved longitudinally in the receiverThe left bolt lug |40 is shown in the locked position engaged withrreceiver locking shoulder |42 in Fig. 24. Fig. 25 shows the left boltlug nearly unlocked from the receiver shoulder |42. During this portionof the unlocking movement the bolt has been cammed toward the rear bythe loW pitch helix |42@ of the receiver acting o-n the front end helix|44 of the left bolt lug |40. Fig. 26 shows the completely unlockedposition of the bolt lug |40 which has been still further cammed towardthe rear by the steep pitch helix |45 of the receiver acting on thehelixV |46 of the bolt'lug. The two stages of camming tothe rearconstitute the primary extraction which, acting through the extractor|41, starts the fired case from th'e chamber |48 of the barrel. Thisprimary extraction movement also serves as an easy transition from vtherotary to the rectilinear motion of the bolt.

Radially extending from the front of right bolt lug. |4| is the arm |49which occupies the helical' cam slot |50 in the enlarged'rear end 85aofthe slide bar 85 which is adapted to move longitudinally on thereceiver, Figs. 13 and 14. Fig.`21 shows the arm. |49 held downwardly bythe rear helix of the cam slot |50. This is the locked arm andcorresponds to the bolt position shownA in Fig. 25.

In the closing cycle of the breech action', when the .cam slot |50 pullsthe bolt forward, the squared ledge |53 of the 'cam slot, Fig. 23, movesforward tocontact the squaredback face |54 of the bolt arm |49 and'tothereby pull the bolt for- Ward without imparting a rotative tendency tothe bolt. During this forward travel, the bolt is held from rotation bythe left bolt lug |4 0"oc cupying the'slot |55' in the receiver asshown4 in, Figs. 26 and 14. l

When the bolt'reaches'nearly` to its forward position,` its left lughelix |46 comesin contact with the helix |45 of the receiver, see Fig.V26.

This contact -deflects thev left vlugf upward -to the Fig. 13 `is afront view of the bolt in itsr with 'the cartridgeY rim.

4rier'204, Which'is slidable in the receiver position shown in Fig. 25.This portion of the rotation of the bolt moves the bolt arm |'49downward off contact with the Aledge |53 of the cam slot |50 to theposition shown in Fig. 22. The continued forward travel of the slidecauses the helix |5| of the cam slot |50 to ride down the bolt.

arm |49 'to the locked position of the bolt as showrr inFig. y21, inrespect-ofthe bolt arm |49 and by-Fig; 24 in respect of the leftbolt lug|40.

It should be understood that the right bolt lug Y, 14|, Figs. 3, 13, 14,is freed from or is in engagement with the right receiver lockingshoulder |43 sh'own'in Fig. 14, simultaneously with the freeing orengagement of the left bolt lug |40 from or with the left receiverlocking shoulder |42.

The -bolt |39 vis rotatably mounted in a bolt car- The extractor |41 ismounted in the bolt in a radially directed T-slot |92, Fig. 3. TheT-slot slopes slightly to the rear and the movement of the extractor'isrigidly controlled so that, as it moves outward from the cartridgerimthe extractor claw |04 moves also slightly to the rear: This rear-Wardinclination ofthe extractor path prevents the claw |94 from slippingoff-the cartridge rim during extraction. The extractorplunger y urgedforward by the extractor springl ISB-tends atl all times, through thecammingfcontactof face |91 of the plunger and surface |98'oftheextractor, to force gthe kextractor into engagement The ejector|99'isat-al1 times lurgedforward by the ejector spring'200'z Therear'end'of the Yspring 200 'is supported by the plunger 20|. The `frontend ofthe plunger furnishesa stop'to limit Vthe rearward movement of'the ejectorl 99. A retain'- ing pin 2,03'fnecked at its mid-portionservesto retain the plunger-`20| linthe bolt when the lbolt is'separatedfrom'the carrier 204; see Figs. 1,A 2, and 4.

The-bolts rear end vrl205-is cylindrical for being journaled-in thecarrierV 204. Thefboltis re.- tained thereinvby thewtoothZGSLOftheU-bolt (Fig. 10) engaging-behind allug 201 of `thefcarrierilig.4) The^forward part offy the lug 201 has` cut therein a segmental recess208 in which the Vrear 'endofthe f plunger 20| rides V `when the boltis` rotatedfrorn*its\'loclted` toits unlockedv position.

Fig.`8 shows the plunger 20| (indottedlines) againstaistop'en'd 209 ofthe recessA 208 thus preventing the-bolt-from rotating'beyond itsunlocked position when the bolt `and Vbolt carrier.vv are removed fromthe receiver. An inclined cut"2 |0 through the-bottom 'of'lug'201,-Figs. 4, Brand 9, allows the introduction'of a pointedI instrument todepressi they plunger 20| againstV`r the tension of its spring 200,'andthuspermitsY-the bolttol be rotated beyondjits' unlocked-=position toits disassembled position, Fig.l 9, wherethe 'tooth 206 on the `bolt'clearsthelug 201- of theicarrier.` The bolt may now bedrawn forward'out of thecarnen The carriery 204, in which the-bolt |39-y is mounted,lhas lonly reciprocatorymotion in the receiver. `A left rib `2|| of thecarrieris constantly guidedinthe slot4 |55-'ofv thereceiver, Figs. 1,2,13,"14,v 17, etc; The slot |55also is the guide for the left bolt lug|40 when the bolt reciprocates its forward position and the rail 2 I0reciprocates back in receiver groove I55a when the bolt is being opened.The cover 202 therefore, aids in the guiding of the carrier 204 in thereceiver.

The cover is assembled onto the carrier prior to the bolt beingassembled to the carrier. The cover has endwise movement on the carrier,between the shoulder 2I'I of the carrier and shoulder 2li:l of the bolt,Figs. 1, 2, and 4. This endwise movement is limited by the rear lug 2 I9 and forward lug 220 of the cover, Fig. 4. When the bolt is back in itsopen position, the cover is moved to its forward limit on the carrier,Figs. 2, 3, and 4. As the bolt moves forward to its `closed position,Fig. 1, the front left end 22| of the cover stops against the shoulder222 of the receiver, Fig. 2, the bolt and carrier continuing to moveforward to the closed position. The cover is held forward to the stop222 of the receiver` by the shoulder 2Il of the carrier, Fig. 1. Therear end of the cover thus extends to the rearward `of the carrier andcovers the space between the rear end of the carrier and the end 223 ofthe receiver opening, Fig. 1, when the bolt is closed.

The firing pin 224 is journaled at its rear portion in the carrier 204and its forward reduced end 226 projects through the bolt face, andfires the cartridge in the chamber when its rear end 225 is struck bythe hammer |27, Fig. 1. The rear end 205 of the bolt is slottedcrossvvise at 221, Figs. 12, 15, and 17. Into this slot engages aflattened intermediate wing 228 of the firing pin. The firing pin,therefore, while it has end movement independent of the bolt, mustrotate with the bolt. The rear end 225 or the firing pin has a laterallug 229 whose forward face is provided with a helical cam 230, Fig. 4.Fig. 19 shows the position of lug 229 when the firing pin is forwardinthe firing position. Fig. 20 sho-ws the position of lug 229 of thefiring pin when the bolt is unlocked, the ring pin having been fullyretracted by the helical cam 23| of the carrier as it rotated with thebolt to the unlocked position of the latter. The firing pin isassemb'led to the carrier from the rear, the flattened wind portion 228entering through grooves 232, 233 in the bore of the carrier, Fig. 6.

The bolt is next inserted into the carrier so that the wing portion 228is picked up by the f cross slot 221 of the bolt. When the bolt isrotated to its unlocked position with respect to the carrier, Fig. 6,the rear shoulders of the wing portion 228 are rotated out ofregistration with the grooves 232, 233 of the carrier 204 to retain thefiring pin in the carrier. The bolt is provided at its forward portionwith bolt stop faces 234, 235, Fig. 10, which are adapted to be engagedby a bolt stop as hereinafter described, for holding the bolt open. Thefront face 234 is shown in end views, Figs. 7, 13, and 14. The rear face235 is carved into the lower left corner of the bolt directly behind thefront face 234 as shown in Figs. 10 and 11.

In Figs. 27 to 37 inclusive, I have shown an alternative form of boltmechanism which may be used for the breech closure in place of thatheretofore described. In this alternate form the bolt carrier isdesigned to perform both the functions of a carrier and that of thecover of my first described bolt mechanism. Consequently, there arefewer parts in this second form--it will be lighter in weight and itscost of manufacture will be less than that of the first form.

CLI

The bolt 400 carries the same sort of locking lugs |40, |4| and radialarm |49 and will have the same action for opening and closing the breechas that previously described. The extractor, spring and plunger are alsothe same excepting that the tail of the plunger 40| has been extendedand flattened to give it a limited r spring action. This tail 40 IVprojects through a bolt hole 402 in position to intercept an inwardflange 403 of the carrier 404 when the carrier is in its forwardposition on the bolt. In this position notch 405 in the carrier flange'403 (Figs. 28 and 30) is occupied by the -tail 40| of the plunger. Thebolt shoulder 406, coacting with the shoulder 401 of the carrier, limitsthe endwise rear movement of the carrier on the bolt. 'Ihe carrierpartlyV surrounds the' bolt and serves as a cover therefor. Thiscarrier-cover member 404 carries two pairs of prongs 408, 409, 4I0, and4| I, Figs. 30, 34, 35, and 37, which embrace the bolt and secure it tothe carrier. When the bolt and attached carrier are removed from thereceiver the carrier may be detached from the bolt by moving the boltback to its limit in the carrier and then rotating the bolt beyond itsunlocked position, Fig. 34. The tail 40| of the plunger, acting againstthe side of the notch 405 of -the carrier, will yieldingly resist thisrotation, to prevent accidental detachment. The bolt may now be furtherrotated and swung downward clear of the carrier around the right handprongs 408, 4 I0, as a pivot, the slots 4|2 and 4|3 being formed in thesurface of the bolt to provide clearances for the carrier prongs 409 and4II.

The firing pin 4| 4 has an upright lug 4 I 5 whose upper endreciprocates in a slot 4I6 of the carrier to prevent rotation of thefiring pin with respect to the carrier. The lug 4I5 has a helix 4II.When the bolt is in its locked position, the ring pin point 4|8 mayprotrude through the bolt face 4I9. In that position the ring pinlug 4I5with respect to the rear end 420 of the bolt is shown by Fig. 32. As thebolt is unlocked its helical cam 42|, coacting with the helix 4II of thefiring pin,

7 retracts the firing pin so that the lug 4I5 rides on the surface 422of the bolt, Fig. 33. The firing pin has a lugy 423, which lies ahead ofshoulder 424 and in a recess 423 in the bolt, to retain the firing pinin the bolt. When the bolt is detached from the carrier the firing pinmay be rotated to free the engagement of the firing pin lug 423 from thebolt shoulder 424 to permit the withdrawal of the firing pin.

The carrier 404 partakes only of sliding movement while the bolt hasboth a rotation in the carrier and a sliding movement relative thereto.The carrier is formed with the rib 425 on its right side near the rearend, which reciprocates in receiver groove I55a. At the left side of thecarrier is the rib 426 which reciprocates in the left receiver groove|55. The receiver grooves are shown in Fig. 17. The rear end of thecarrier serves to close the space between the rear end of the bolt andthe end 223 of the opening of the receiver, Fig. 1,.

The ejector 421 is mounted in a lengthwise drilled hole 436 of the boltas shown in Fig. 28. It is assembled through the front end of the bolt,after the ejector spring 428 and the plunger 429 are inserted. Inassembled position a truncated cone head 430 of the plunger 429 engagesabove an inclined shoulder 43| at the tail of the ejector and displacesthe rear end of the ejector downward so that a hook 432 thereof willcatch against a"squared.up shoulder 433 of yafradially drilled hole M34`infthe bolt, Fig528. When the frontend 435 of the ejector is forcedrearward-.- lyfbyaicartridge head, the rear end of the plungier:;429;abuts the bottom 4310i the hole 436and limits :the inward rnovementof`the ejector. In disassembly, a pointed tool is pressed'. throughhole-434` against the bottom rear end of thezejecgtorand .forces the'hook 432 above they squared upshou1derf433, whereby the ejectorlWilldrop outforwardly from the hole 43E-vin the bolt.

I claim:

1`.- The combination with the receiver of a rifle of `albreech closuretherefor comprising a bolt, a bolt carrier in which said bolt isrotatably mounted., y.acover telescopically engaged with said boltcarrier and .arranged to rbe in extended relation thereto when thebreechiszclosed and in collapsed bolt-carrier being slidably engaged'inka wayof said. receiver at one side thereof by a single lateral rib formed `onsaid bolt carrier and said cover being slidably` engaged vin a .Way ofsaid rerelationthereto when the breech is open, said l ceiver atVthezother side;thereof*byfafsngle'lateral rib formed on'sad cover. Y YY Y 2. Thecornbinaton with the receiver-of a'riiie of a breech closuretherefor, ,comprisingarbolt a bolt carrier Whchalso serves as -a cover,means for mountingI said bolt: carrier in saidreceiver for reciprocableandV non-rotative movement therein,.,means for-mountingsaidsbolt in saidbolt carrier so- `that said bolt 4mayhaveboth rotatable and slidablemovement-therein, saidbolt and bolt carrier arranged to'be'inextendedrelation toone another when the bolt'is inbreech closing position and in.collapsed relation vto4 one another when thefboltis in;position'of.-a'full open breech, `the means for mountingsaid bolt in: said-boltcarrier comprising a` cylindrical por-

